A scroll fluid machine described in JP-A No. 2004-92480 includes a lip that is formed by making a linear cut in the seal to prevent leakage into a recessed groove formed on a tooth top of a wrap for the bottom surface of a sealing member. When compressed air in a compression chamber enters the recessed groove, the sealing member rises in such a manner that its upper side surface slidingly contacts the tooth bottom land on the other side, and the leading end of the lip is pressed against the bottom surface of the recessed groove. Thus, an airtight seal is formed between the tooth bottom land and the wrap on the other side.
Another scroll fluid machine, which is described in JP-A No. H7-229485, includes a fin-shaped lip that is placed on the bottom surface of a sealing member and uniform in thickness. Still another scroll fluid machine, which is described in JP-A No. H10-47266, includes a lip that is formed by making a curved (arc-shaped) cut in the bottom and lateral surfaces of a sealing member.